window.onload=function(){
    var dd = true;
    window.onscroll = function () {
        scrollTop = document.body.scrollTop+document.documentElement.scrollTop;
        if(dd){
            document.getElementById("Mask").style.top = scrollTop+"px";
        }
    }
    //微信提示干扰问题的解决
    var length1 = document.getElementsByTagName("input").length;
    for(var d = 0; d<length1; d++){
        document.getElementsByTagName("input")[d].onfocus = function () {
            dd = false;
        }
    }
    var length2 = document.getElementsByTagName("select").length;
    for(var f = 0; f<length2; f++){
        document.getElementsByTagName("select")[f].onfocus = function () {
            dd = false;
        }
    }
}